William starts counting at 38, and he counts by fours. If 38 is the 1st number that William counts. what is the 13th number that he counts?
What is the first number that he counts? $38$ What is the second number that he counts? $\begin{align*}&38 + 4 \\ &= 42\end{align*}$ What is the third number that he counts? $\begin{align*}&38 + 4 + 4 \\ &= 38 + (2 \times 4) \\ &= 46\end{align*}$ What is the 13th number that he counts? $\begin{align*}&38 + (12\times4) \\ &= 38 + 48 \\ &= 86\end{align*}$